Cancer is one of the leading cause of death in the United States. Most cancer starts in just a single neoplastic cell. The neoplastic cell proliferate to form a local “tumor.” A tumor simply means a swelling; it is not necessarily cancerous. A tumor which only grows in its place or origin, and cannot spread distantly, is a benign tumor and is not cancer. However, a tumor which has the capacity to spread (whether it actually does or not) is called a malignant tumor or cancer. A cancer may spread via the blood or lymphatic system to regional lymph nodes and to distant sites via a process called metastasis. A metastasized cancer is more difficult to treat because it now spreads into many different tissues and organs. It has been demonstrated that early treatment increase survival in many types of cancers, such as breast cancer, colon cancer, ovarian cancer and prostate cancer.
Chemokines are a superfamily of small, cytokine-like proteins that are resistant to hydrolysis, promote neovascularization or endothelial cell growth inhibition, induce cytoskeletal rearrangement, activate or inactivate lymphocytes, and mediate chemotaxis through interactions with G-protein coupled receptors. Chemokines can mediate the growth and migration of host cells that express their receptors.
Chemokine (C-C motif) ligand 25 (CCL25), also known as Thymus-Expressed Chemokine (TECK), is a small cytokine belonging to the CC chemokine family. CCL25 is chemotactic for thymocytes, macrophages, and dendritic cells. CCL25 elicits its effects by binding the chemokine receptors CCR9 and is believed to play a role in the development of T-cells. Human CCL25 is produced as a protein precursor containing 151 amino acids. The gene for CCL25 (scya25) is located on human chromosome 19.
Chemokine (C-C motif) receptor 9 (CCR9), also known as GPR 9-6, is very highly expressed in thymus (on both immature and mature T-cells) while low in lymph nodes and spleen. CCR9 is also abundant in the gut, with its expression associated with T cells of the intestine. To note, the chemokine binding protein D6 had previously been referred to as CCR9, but this molecule is a scavenger receptor not a true (signaling) chemokine receptor.